title: Self-assembled micellar nanoparticles of a novel star copolymer for thermo and pH dual-responsive drug release.
abstract: An amphiphilic star block copolymer comprised of a hydrophobic PMMA block and a hydrophilic tri-arm poly(NIPAAm-co-DMAEMA) block was synthesized by copolymerization of NIPAAm and DMAEMA, with Ce(4+) ions and tris(hydroxymethyl)methylamine as a redox initiatory system. The star copolymer undergoes self-assembly to the micellar nanoparticles with a core-shell structure and the thermo/pH dual-response, originated from the thermo-sensitivity of PNIPAAm and the pH-sensitivity of PDMAEMA. A fluorescence probe study showed the pH-dependent low CMCs (7.5 to 11.2 mg/L) of the micelles, confirming the formation of stable micelles. Morphological investigations showed that the blank and drug-loaded micelles both had spherical and uniform shapes. The sizes of the blank and drug-loaded nanoparticles were between 80 and 120 nm, depending on the given pH. The LCSTs of the star copolymer were determined to be 32 degrees C, 36.6 degrees C and 39.5 degrees C, corresponding to pH 5, pH 7.4 and pH 9, respectively, demonstrating a pH-dependent thermo-response. As a drug delivery, the micellar nanoparticles showed the dual-responsive release profiles in vitro, which were confirmed by the drug release studies. The obtained results showed the thermo-triggered accelerated release at pH 7.4, and the pH-triggered accelerated release at 37 degrees C, indicating the micelles nanoparticles would be a promising site-specific drug delivery for enhancing the accumulation of drug in targeting pathological areas.
authors.affiliation: Department of Applied Chemistry, East China Institute of Technology, Fuzhou 344000, PR China. yhliu@ecit.edu.cn
authors.forename: Yunhai
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Cao
authors.forename: Mingbiao
authors.initials: M
authors.lastname: Luo
authors.forename: Zhanggao
authors.initials: Z
authors.lastname: Le
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Xu
mesh_terms: D003692:Delayed-Action Preparations / Q000493:pharmacokinetics*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry* / Q000627:therapeutic use; D011108:Polymers; D013696:Temperature
chemical_list: D003692:Delayed-Action Preparations; D008823:Micelles; D011108:Polymers